Selection of phase change materials, metal foams and geometries for improving metal hydride performance

Abstract

This paper reports the numerical investigation of the effect of different phase change materials (PCMs) on the metal hydride (MH) behaviour in a reactor bed during the absorption process. The feasibility of integrating metal foams (MFs) into the phase change materials to improve the hydrogen storage performance of the system was also evaluated. A two-dimensional model for a LaNi5 hydride reactor equipped with different phase change materials has been developed. The selection of five different PCMs having a high latent heat of fusion and a range of melting temperatures were investigated. In addition, the effect of the mass and volume of the different PCMs on the hydrogen performance of the MH reactor was studied. It was found that LiNO3·3H2O PCM shown better performance than the other PCMs, its loading time is faster, and its mass within the reactor is enough to absorb the total heat generated from the MH during hydrogenation. Three different metals foam with three different porosities were integrated into the most suitable PCM with the appropriate dimension of a cylindrical reactor that shows the optimum performance. The obtained results indicated that the integration of the metal foams into the PCM show better heat transfer performance than the case of MH-PCM without metal foams. Two different configurations cylindrical and spherical MH reactors were investigated. The obtained results indicated that the two configurations have very similar behaviours. So, both configurations are good for the hydriding process within an MH reactor.